Biomass is a mass of renewable and recurrent organic matter. It includes trees, plants and the residues associated with them; vegetal fibres, animal and industrial wastes, and the organic portion of the solid urban wastes. It comes from 3 sources :

• Forestry biomass composed of waste from the forest such as the top of braches, trees that have no commercial value or that cannot be sold (individually or as a group), the leftover wood, the residues resulting in the thinning out of trees, the lumbering by-products such as bark, sawdust and the leftovers of the wood transformation industry.
• Agricultural biomass including the harvesting wastes, the "energetic" cultures along with the other organic debris like animal wastes (manure, dung…).
• Urban biomass, such as solid urban garbage is considered a source of biomass. When eliminating solid wastes by combustion, we obtain electricity. The gas of burying is emitted after the airless decomposition of organic matter found in the burial ground. Caught and torched, the gas produces electricity.